In the global health landscape, chronic pain and depression stand out as two of the leading causes of disability (GBD 2016 Disease and Injury Incidence and Prevalence Collaborators 2017). Chronic lower back pain in particular has been identified as the primary cause of disability, affecting millions worldwide. Simultaneously, depression remains one of the main drivers of suffering on a global scale, a situation worsened since the COVID-19 pandemic (Dragioti et al. 2022).
Beyond the profound impact these conditions have on quality of life and the economic sustainability of healthcare systems, the scientific community—including our UMSS research group—has paid close attention to the intricate comorbidity between them. A revealing statistic highlights that while chronic pain affects approximately 20% of the general population, its prevalence rises to 65% in patients with depression (Thompson et al. 2016).
Despite this clear connection, the pathophysiological mechanisms underlying this relationship are far from fully understood. A deeper understanding of these processes could lead to more effective prevention and treatment strategies, ultimately reducing the health and economic burden posed by these two conditions.
Nociceptive Processing: A Model to Understand Comorbidity
One of the most studied models explaining the comorbidity between depression and pain focuses on alterations in nociceptive processing.
Nociception is the process by which the nervous system detects and encodes potentially harmful stimuli. Specialized receptors, called nociceptors, capture information about harmful stimuli and transmit it to the brain (Armstrong & Herr 2024). However, while nociception is fundamental to the perception of pain, it is the brain’s interpretation of this information that ultimately determines the pain experience. This interpretive process is complex, influenced by factors such as the context of stimulation, the patient’s cultural beliefs, past experiences, and potentially their mental health status (Yalcin & Barrot 2014).
In patients with depression, structural and functional alterations have been observed in key brain regions involved in nociceptive processing, which could partially explain their heightened vulnerability to chronic pain. For instance, altered activity levels have been reported in the medial prefrontal cortex, a crucial region for activating the body’s natural analgesic response (Pizzagalli & Roberts 2022). This suggests that individuals with depression may have a reduced capacity to modulate pain, increasing their risk of chronic pain. However, the limited scientific literature on this topic has yet to offer definitive conclusions.
Looking Ahead
In the coming years, the increasing accessibility of advanced research tools, such as neuroimaging, is expected to shed light on these mechanisms. At UMSS, we are excited about contributing not only to the scientific understanding of this complex relationship but also to the dissemination of these findings.
